The carbonaceous material comprises carbon nanotube, active carbon, graphite, graphene, fullerene, nano-carbon fiber and nano-adamas or the like. The carbonaceous material can be used as the catalytic material for oxidation of alkanes, for example, the active carbon can be used as a catalyst for oxidative dehydrogenation of ethylbenzene to produce styrene, and the active carbon can be used as a catalyst for conversion of n-butane to butene and butadiene.
The investigations show that the modification of the surface of the nano-carbon material (e.g. carbon nanotube and graphene) with a saturated and non-saturated functional group containing the heteroatoms such as oxygen and nitrogen can change the catalytic activity of the nano-carbon material. The nano-carbon material can be oxidized to introduce the oxygen atom into the nano-carbon material and increase the amount of the oxygen-containing functional groups in the nano-carbon material. For example, the nano-carbon material can be treated in a reflux condition of a strong acid (e.g. HNO3, H2SO4) and/or a strong oxidative solution (e.g. H2O2, KMnO4) optionally in the help of the microwave heating or the ultrasonic oscillation to enhance the oxidation effect.
However, the reflux treatment in the strong acid and/or the strong oxidative solution will have a negative effect on the framework structure of the nano-carbon material, and even destroy the framework structure of the nano-carbon material. For example, the oxidation of the nano-carbon material in a nitric acid solution can introduce a large amount of oxygen-containing functional groups to the surface of the nano-carbon material, but said treatment will be apt to cut off the nano-carbon material and/or remarkably increase the defect sites in the graphite network structure, and therefore reduce the properties of the nano-carbon material, e.g. thermostability. In addition, the amount of the oxygen atoms introduced by the reflux treatment in the strong acid and/or the strong oxidative solution has a high dependency on the reaction conditions, and will fluctuate widely, resulting in the difficulty of accurate control.
Olefins, especially diolefins and aromatic olefins, are important chemical feedstocks. For example, butadiene is a main raw material in production of synthetic rubbers such as styrene-butadiene rubber, butadiene rubber, nitrile rubber and chloroprene rubber. The copolymerization of styrene and butadiene to produce various widely used resins (e.g. ABS resin, SBS resin, BS resin and MBS resin) gradually plays an important role in production of resins. In addition, butadiene can also be used to produce ethylidene norbornene (a third monomer for ethylene propylene rubber), 1,4-butanediol, adiponitrile (nylon 66 monomer), sulfolane, anthraquinone and tetrahydrofuran, and butadiene is also an important basic chemical raw material. In addition, styrene is an important monomer in synthetic rubber and plastic, and can be used to produce styrene-butadiene rubber, polystyrene, polystyrene foam and the like. Styrene can be copolymerized with other monomers to produce engineering plastic for different uses, for example, styrene can be copolymerized with acrylonitrile and butadiene to produce ABS resin for use in a variety of household appliances and industry; with acrylonitrile to produce the SAN resin which is a resin having an impact resistance and a bright color and shade; and with butadiene to produce the SBS rubber, which is a thermoplastic rubber widely used as the modifier for polyvinyl chloride, polypropylene and the like. Styrene is mainly used in production of styrene resin and styrene butadiene rubber, but it is also one of raw materials in production of ion exchange resin and pharmaceutical. Moreover, styrene can be also used in pharmaceutical, dyes, pesticides and mineral processing industries.
Oxidative dehydrogenation is an important method for the production of olefins. For example, butane can be subjected to the oxidative dehydrogenation to produce 1-butene, which can be further subjected to the oxidative dehydrogenation to produce 1,3-butadiene; or phenylethane can be subjected to the oxidative dehydrogenation to produce styrene. However, the existing problem in the oxidative dehydrogenation to produce olefins is the difficulty in increasing both of the selectivity and the conversion, i.e., the difficulty in increasing the selectivity while increasing the conversion.